Node structure information management method and radio network system

ABSTRACT

A node configuration information management method and a wireless network system whereby node configuration information about a wireless bus comprising a hub station and a plurality of nodes is managed by the hub station in a centralized manner so that the hub station can share the latest node configuration information with all of the nodes. According to the node configuration information management method, when the node information in the wireless bus  11  is modified, a node notifies the hub station of the modification via a modification notifying packet. Further, 1) Each node and the hub station store the node configuration information about each node in a node configuration information table, and the hub station has a counter for managing the updating of the node configuration information table as a whole and transmits a count in each frame; 2) The hub station, upon reception of the node configuration modification notification from the node, updates its own node configuration information table, and broadcasts update information to all of the nodes; 3) The node receives the modification information and updates its own node configuration information table, while receiving the count transmitted in each frame, determining if there is updating on the part of the hub station, requesting retransmission of differential information concerning the difference, if any, from its own node configuration information table, and updating its own node configuration information table.

TECHNICAL FIELD

The present invention relates to a method of managing node configurationinformation in a wireless network environment comprised of a hub stationand a plurality of terminals, whereby the node configuration informationin the network is managed by the hub station in a centralized manner.The invention also relates to a wireless network system.

BACKGROUND ART

Recently, attention is being focused on network systems in whichmultiple electrical household appliances are connected by cables fortransmission and reception of voice and image data. For example, it isnow common to watch videos shot with a digital video camera byconnecting the camera to a monitor by cables, or to edit images byconnecting the camera to a video apparatus. More recently, there is atrend of building such network systems not with cables but wirelessly.Wireless transmission and reception provides an advantage in that thetroublesome aspects of wiring devices can be eliminated. An example ofsuch a wireless network (to be referred to as a wireless bus) will bedescribed below.

FIG. 32 shows a block diagram of a configuration of terminals and a hubstation in a wireless bus. Numeral 1 designates a wireless bus (wirelessnetwork), 2 a hub station, and 3–6 nodes formed by multiple terminals.The wireless bus 1 includes a plurality of devices called nodes, andmultimedia data is transmitted and received among the nodes. Thetransmission and reception of the data are managed by the hub station 2.In order to enable inter-node wireless communication, the nodes 3 to 6in the wireless bus 1 have memory regions for storing node configurationinformation concerning the wireless bus 1, node information about eachnode, and inter-node communication quality information. The hub station2 is selected from those of the nodes 3 to 6 in the wireless bus 1 thathave the functions required of a hub station. One prerequisite for anode to become the hub station 2 is that the node be located at aposition that allows it to communicate with every other node in thewireless bus 1. The hub station 2 is also required to have functions forgathering and analyzing the node configuration information, nodeinformation for each node, and inter-node communication qualityinformation transmitted from the nodes 3 to 6, so that it can manage thelatest information.

Hereafter, the node configuration information, node information, andinter-node communication quality information managed by the hub station2 will be described.

The node configuration information indicates whether or not theindividual nodes 3 to 6, which are centrally managed by the hub station2, can carry out communication. When there is a change in the nodeconfiguration in the wireless bus 1, such as when a node is newlyregistered or deleted, the node configuration information is updated.The node information indicates the function of each node. Of the nodesparticipating in the wireless bus 1, some have the functions of the hubstation 2, some have relay capability, and some have only anasynchronous communication function. In order to build the wireless bus1, it is necessary to check the functions of the individual nodes andthen select a hub station from among the nodes having a managementfunction.

The node configuration information and the node information are updatedonly when a node is newly registered or deleted in the wireless bus 1,or the function of a node is changed. These items of information are notmodified for any other reason.

The communication quality information indicates the states ofcommunication condition between individual nodes when data istransmitted or received wirelessly. When a wireless bus is constructedin a wireless environment, it is necessary to select an appropriatetransmission method adapted to the conditions of communication paths, sothat accurate transmission and reception can take place. However, awireless transmission path could deteriorate when a node has beentransported or when there are people or obstacles located between twonodes, for example, making it impossible to transmit or receive data.Thus, the communication path conditions among the individual nodes varyon a case-by-case basis, and so the hub station must receive thecommunication path conditions from the nodes and manage them.

As an example of the method of managing the information mentioned above,JP Patent Publication (Unexamined Application) No. 11-88396 discloses anapparatus for managing node configuration information in a network of aplurality of nodes connected by cables. In this example, each nodecarries a table for the management of the node configuration informationin the network. Each time the node configuration is updated, the nodeconfiguration information is transmitted to other nodes, so that thereare no discrepancies regarding the node configuration informationcarried by the individual nodes in the network. This example is wiredand involves only node configuration information. Further, JP PatentPublication (Unexamined Application) No. 11-215135 discloses a method ofmanaging the quality of individual communication paths in a wirelessnetwork comprised of a plurality of nodes. In this example, a hubstation is selected from among the multiple nodes, and the hub stationcentrally manages the communication path quality information in thewireless network. Each node in the wireless network transmits its ownmanagement information to all of the other nodes. Each node receives themanagement information from all of the other nodes in the wirelessnetwork and evaluates it. The nodes then transmit management informationresults to the hub station, which in turn overwrites this information onthe communication quality information table. This example is wirelessand involves only communication quality information.

These conventional node configuration information management methodshave the following problems. In the communication apparatus disclosed inJP Patent Publication (Unexamined Application) No. 11-88396, each timethe node configuration is updated as the number of nodes increases, nodeconfiguration information corresponding to the number of nodes must betransmitted. This results in an increase in overhead. Further, the hubstation must wait until it receives an Ack signal from all of the nodesto which the hub station has transmitted.

While this management method creates no problems in the case of wiredexamples, it would not be an efficient method for wireless communicationwith limited frequency resources, because no other data can betransmitted while waiting for an Ack signal. Further, in a wiredenvironment using cables, for example, the communication conditionsamong the nodes are fixed, so in this case there is no need to recognizethe communication quality conditions. For these reasons, there is nodescription of a method of managing communication quality information.On the other hand, JP Patent Publication (Unexamined Application) No.11-215135, which relates to a wireless communication method, does notdescribe the method of managing node configuration information. It ispossible to transmit node configuration information by adding it to theabove-described communication quality information. However, while thecommunication quality information varies depending on communicationconditions, node configuration information is updated upon registrationof a new node, deletion of a node, or when there is a change in a node.Accordingly, inserting the node configuration information in each frameand thus notifying the hub station would be redundant and could not becalled an efficient method for wireless communication with limitedfrequency resources.

In view of these problems of the prior art, it is an object of theinvention to provide a node configuration information management methodand a wireless network system whereby node configuration information ina wireless bus comprised of a hub station and multiple nodes is managedby the hub station in a centralized manner. This is carried out in amanner such that the hub station can share the latest node configurationinformation with all of the nodes.

It is another object of the invention to provide a node configurationinformation management method and a wireless network system whereby nodeconfiguration information in a wireless bus comprised of a hub stationand multiple nodes is centrally managed by the hub station in eachframe. This is carried out in a manner such that the hub station canshare the latest node configuration information with all of the nodes inthe wireless bus within a minimum frame.

SUMMARY OF THE INVENTION

A method of managing node configuration in a wireless network accordingto the invention comprises a hub station and a plurality of nodes,wherein the hub station has a hub station management table for managingunique information about each of the nodes, wherein the updating of thehub station management table is managed by first update timinginformation which is transmitted to all of the nodes periodically,wherein if the hub station management table is modified, modificationinformation is transmitted to all of the nodes together with the firstupdate timing information, wherein each node has a node management tablefor managing the unique information about the node, wherein the nodereceives the first update timing information and the modificationinformation, compares the first update timing information in its ownmanagement table with the first update timing information transmittedfrom the hub station, and rewrites its own management table based on themodification information if its own update timing information is older.

According to this method, even if a node has failed to receive thedifferential unique information transmitted from the hub station, thenode can acquire the subsequently transmitted update timing and compareit with the update timing possessed by the node, so that the node canrecognize that its own table is old. Thus, because the differentialportion of the unique information is transmitted only when there is amodified portion, the node configuration information can be managedwithout requiring any redundant data transmission.

A method of managing node configuration in a wireless network accordingto the invention comprises a hub station and a plurality of nodes,wherein

the hub station has a hub station management table for managing uniqueinformation about each of the nodes, wherein the updating of the hubstation management table is managed based on first update timinginformation that is transmitted to all of the nodes periodically,wherein

each node has a node management table for managing the uniqueinformation about the node, wherein the node receives the first updatetiming information and compares the first update timing information inits own management table with the first update timing informationtransmitted from the hub station, wherein the node requests thetransmission of the unique information data if its own update timinginformation is old, and rewrites its own management table based on theunique information data transmitted from the hub station in response tothe request.

According to this method, when a node has failed to receive the updatedata, the node requests the hub station to transmit differential data inthe unique information. Thus, even if a node has failed to receive thelatest unique information as a differential portion, the node canrequest the retransmission of the differential unique information andupdate based on the returned unique information, thus enabling accuratemanagement of the node configuration information.

More preferably, the unique information data transmitted from the hubstation in accordance with the request from the node for the uniqueinformation data is differential data including only the uniqueinformation about a node that has been added, modified, or deletedsubsequent to the update timing information possessed by the node. Thus,because the differential unique information is transmitted only whenthere is a modified portion, the node configuration information can bemanaged without carrying out redundant data transmission.

A method of managing node configuration in a wireless network accordingto the invention comprises a hub station and a plurality of nodes,wherein

the hub station has a hub station management table for managing theunique information about each node, wherein the updating of the hubstation management table is managed based on first update timinginformation, wherein

each node has a node management table for managing unique informationabout each node, wherein the updating of the node management table ismanaged based on the first update timing information, the nodeperiodically transmitting the first update timing information that itmanages to the hub station, wherein

the hub station compares its own first update timing information withthe first update timing information transmitted from each nodeperiodically, the hub station creating the unique information data ifthe two items of information are different and transmitting it to thecorresponding node, wherein

the node rewrites its own management table based on the data transmittedfrom the hub station.

Preferably, the hub station compares the first update timing informationperiodically transmitted from each node with its own first update timinginformation, and, if there is a difference, the hub station createsunique information differential data corresponding to the difference andtransmits it to the relevant node.

Preferably, the hub station periodically transmits the first updatetiming information to all of the nodes and, if the management table ismodified, the hub station transmits modification information to all ofthe nodes together with the first update timing information.

Thus, the hub station transmits the node configuration updateinformation together with the update timing. The node periodicallytransmits the update timing to the hub station. The hub station comparesits own update timing, and retransmits the update information to anynodes that are not synchronized. In this way, information can be managedreliably.

Further, the first update timing information may be sequentiallyupdated, wherein, if the first update timing information of the node isolder than the first update timing information transmitted from the hubstation by more than two, the node requests the hub station, togetherwith the update timing information of its own, to transmit the relevantdifferential data. In this way, even if a node has failed to receive theunique information twice or more that is transmitted as a differentialportion, the node can recognize this fact by comparing its own updatetiming with the update timing transmitted from the hub station. The nodecan then request the hub station to undertake retransmission togetherwith its own update timing, acquire the differential data, and updateits own management table. Thus, information can be accurately managed.

The hub station may manage the updating of the unique information abouteach node based on second update timing information in the hub stationmanagement table, wherein the hub station compares the first updatetiming information transmitted from each node with the second updatetiming information of the relevant node in order to select differentialdata. In this manner, the node configuration information can beaccurately managed.

More preferably, the hub station may compare the update timingtransmitted from the node with the second update timing and select thedifferential data if its own is older.

A frame structure for wireless communication includes a region fortransmitting the first update timing information managed by the hubstation to all of the nodes, a region for transmitting the uniqueinformation about each node, a region for the hub station to transmitmodified portion of the unique information to all of the nodes, and adata region for transmitting and receiving normal data, wherein eachnode makes a retransmission request to the hub station individuallyusing the data region, the hub station transmitting differential data inresponse to the retransmission request made using the data region. Inthis manner, the node configuration information can be accuratelymanaged.

Further, a frame structure for wireless transmission includes a regionfor transmitting the unique information about each node, a region forthe hub station to transmit a modified portion of the unique informationto all of the nodes, and a data region for transmitting and receivingnormal data, wherein the node makes a retransmission request to the hubstation individually using the data region, the hub station transmittingdifferential data in response to the retransmission request made usingthe data region. In this manner, information can be accurately managed.

A wireless network system according to the invention comprises a hubstation and a plurality of nodes, wherein

the hub station has a hub station management table for managing uniqueinformation about each node based on first update timing information, adetection means for detecting a modification in the node configuration,an update means for updating the hub station management table inaccordance with the result of detection by the detection means, and atransmitter for transmitting, if there is a modification in the hubstation management table, modification information to all of the nodestogether with the first update timing information, as well astransmitting the first update timing information to all of the nodesperiodically, wherein

each node has a node management table for managing the uniqueinformation about the node based on the first update timing information,a receiver for receiving the first update timing information, and anupdate means for comparing the first update timing information in thenode management table of the node with the first update timinginformation transmitted from the hub station and for updating, if theupdate timing information of the node is old, its own node managementtable based on the modification information.

A wireless network system according to the invention comprises a hubstation and a plurality of nodes, wherein

the hub station has a hub station management table for managing uniqueinformation about each node based on first update timing information, adetection means for detecting a modification in the node configuration,an update means for updating the hub station management table inaccordance with the result of detection by the detection means, and atransmitter for transmitting the first update timing information to allof the nodes periodically, wherein

each node has a node management table for managing the uniqueinformation about the node based on the first update timing information,a receiver for receiving the first update timing information, a datatransmission request means for comparing the first update timinginformation in the node management table of the node with the firstupdate timing information transmitted from the hub station and forrequesting, if the update timing information of the node is old, thetransmission of the unique information data, and an update means forupdating its own node management table based on the unique informationdata transmitted from the hub station in accordance with the request.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of the structure of a wireless buscomprising terminals and a hub station according to the nodeconfiguration information management method in the first embodiment ofthe invention.

FIG. 2 shows the structure of a frame that is transmitted or received inthe wireless bus according to the node configuration informationmanagement method in the first embodiment of the invention.

FIG. 3 shows in detail the structure of a frame start packet that thehub station inserts into a frame start region of the frame structureaccording to the node configuration information management method in thefirst embodiment of the invention.

FIG. 4 shows in detail the structure of a node configurationmodification notifying packet that a node inserts into a nodeconfiguration modification region of the frame structure according tothe node configuration information management method in the firstembodiment of the invention.

FIG. 5 shows the structure of a node configuration information requestpacket that a node inserts into a data region in the frame structureaccording to the node configuration information management method in thefirst embodiment when the node requests retransmission from the hubstation.

FIG. 6 shows the structure of a node configuration information updatepacket 60 which the hub station broadcasts using a node configurationinformation transmission region in the frame structure according to thenode configuration information management method in the firstembodiment.

FIG. 7 shows node configuration information management blocks on thepart of the hub station according to the node configuration informationmanagement method in the first embodiment.

FIG. 8 shows node configuration information management blocks on thepart of a node according to the node configuration informationmanagement method in the first embodiment.

FIG. 9 shows the details of a node configuration information table ownedby the hub station according to the node configuration informationmanagement method in the first embodiment.

FIG. 10 shows the details of a node configuration information tableowned by a node according to the node configuration informationmanagement method in the first embodiment.

FIG. 11 shows a node configuration information managing sequencestarting from when the node configuration is updated to when the updatedconfiguration is transmitted to all of the nodes in the wireless busaccording to the node configuration information management method in thefirst embodiment.

FIG. 12 shows a flowchart of the sequence of a node informationnotifying process (1) on the part of a node according to the nodeconfiguration information management method in the first embodiment.

FIG. 13 shows a flowchart of the sequence of a node configuration updateprocess (2) on the part of the hub station according to the nodeconfiguration information management method in the first embodiment.

FIG. 14 shows a flowchart of the sequence of a frame start regionprocess (3) on the part of the hub station according to the nodeconfiguration information management method in the first embodiment.

FIG. 15 shows a flowchart of the sequence of a node configurationinformation update process (4) on the part of a node according to thenode configuration information management method in the firstembodiment.

FIG. 16 shows a flowchart of the sequence of a retransmission process(5) on the part of the hub station according to the node configurationinformation management method in the first embodiment.

FIG. 17 shows the structure of a frame that is transmitted or receivedin a wireless bus according to a second embodiment of the invention.

FIG. 18 shows in detail the structure of a frame start packet that thehub station inserts into a frame start region of the frame structureaccording to the node configuration information management method in thesecond embodiment of the invention.

FIG. 19 shows in detail the structure of a node configuration packetthat a node inserts into a node configuration information modificationregion of the frame structure according to the node configurationinformation management method in the second embodiment of the invention.

FIG. 20 shows the structure of a node configuration information updatepacket that the hub station inserts into a data region of the framestructure according to the node configuration information managementmethod in the second embodiment of the invention when retransmitting toa node.

FIG. 21 shows the structure of a data region in the frame according tothe node configuration information management method in the secondembodiment.

FIG. 22 shows node configuration information managing blocks on the partof the hub station according to the node configuration informationmanagement method in the second embodiment.

FIG. 23 shows node configuration information managing blocks on the partof a node according to the node configuration information managementmethod in the second embodiment.

FIG. 24 shows the details of a node configuration information tableowned by the hub station according to the node configuration informationmanagement method in the second embodiment.

FIG. 25 shows the details of a node configuration information tableowned by a node according to the node configuration informationmanagement method in the second embodiment.

FIG. 26 shows a node configuration information managing sequenceaccording to the node configuration information management method in thesecond embodiment of the invention.

FIG. 27 shows a flowchart of the sequence of a node informationnotifying process (6) on the part of a node according to the nodeconfiguration information management method in the second embodiment ofthe invention.

FIG. 28 shows a flowchart of the sequence of a node configuration updateprocess (7) on the part of the hub station according to the nodeconfiguration information management method in the second embodiment ofthe invention.

FIG. 29 shows a flowchart of the sequence of an update procedure (8) onthe part of a node according to the node configuration informationmanagement method in the second embodiment of the invention.

FIG. 30 shows a flowchart of the sequence of a node configurationinformation synchronizing process (9) on the part of the hub stationaccording to the node configuration information management method in thesecond embodiment of the invention.

FIG. 31 shows a flowchart of the sequence of a retransmission process(10) on the part of the hub station according to the node configurationinformation management method in the second embodiment of the invention.

FIG. 32 is a block diagram showing the structure of a wireless buscomprising terminals and a hub station according to a conventional nodeconfiguration information management method.

BEST MODES OF CARRYING OUT THE INVENTION

Hereafter, preferred embodiments of the node configuration informationmanagement method according to the invention will be described byreferring to the attached drawings.

FIRST EMBODIMEMT

FIG. 1 shows a block diagram of a configuration of terminals and a hubstation in a wireless bus according to a first embodiment of theinvention. While the configuration is similar to the one shown in FIG.32, it differs from the prior art example in the frame structure (FIG.2) used for wireless communication. In FIG. 1, numeral 11 designates awireless bus (wireless network), numeral 12 designates a hub station,and numerals 13 to 16 designate nodes formed by a plurality ofterminals.

A plurality of devices called nodes exist in the wireless bus 11. Thenodes transmit or receive multimedia data among them. The transmissionand reception of data are managed by the hub station 12, which isselected from among the nodes 13 to 16 in the wireless bus 11 that havethe functions required of a hub station. A prerequisite for a node tobecome the hub station 12 is that the node be located at a position thatallows it to communicate with every other node in the wireless bus 1.Further, the hub station 12 is required to be capable of gathering andanalyzing the node configuration information, node information for eachnode, and inter-node communication quality information transmitted fromthe nodes 13 to 16 in order to manage the latest information. Thedetails of the blocks for the management of the node configurationinformation in the hub station 12 will be described later by referringto FIG. 7.

The nodes 13 to 16 in the wireless bus 11 have memory regions forstoring the node configuration information in the wireless bus 11, thenode information for each node, and the inter-node communication qualityinformation, in order to enable the nodes to wirelessly communicate withone another. The details of the blocks for the management of the nodeconfiguration information for the nodes 13 to 16 will be described laterby referring to FIG. 8.

FIG. 2 shows an example of the structure of a frame that is transmittedor received in the wireless bus 11 according to the present embodiment.As shown, a wireless signal with this frame structure 20 is divided intoa frame start region 21, a node configuration modification region 22, acommunication quality information region 23, a node configurationinformation transmission region 24, and a data region 25. The hubstation 12 signals the start of a frame by using the frame start region21 in each frame. The hub station 12 transmits a frame start packet.

FIG. 3 shows the detailed structure of a frame start packet 30 insertedin the frame start region 21 by the hub station 12 in the framestructure of FIG. 2. In FIG. 3, the frame start region 21 has a headposition detection region 31 for storing a head position detectionsignal, a size notification region 32 for storing a size notificationsignal, and a count (C) region 33 for storing a count (C). The headposition detection region 31 is a region that is used for notifying allof the nodes in the wireless bus 11 of the start of a frame. Byreceiving this head position detection signal, each of the nodes in thewireless bus 11 identifies the start position of a frame. The sizenotification region 32 is a region that is used for transmitting thesize of each of the subsequently transmitted, variable-size regions inthe frame. Based on this size notification signal, each node in thewireless bus 11 can identify the subsequent frame configuration. Thecount (C) region records a count (C) (first update timing information)recorded in the hub station 12. Each node in the wireless bus 11acquires the count (C) transmitted from the hub station 12 and confirmswhether its own node configuration update information is up to date.

FIG. 4 shows the detailed structure of a node configuration modificationnotifying packet 40 that is inserted into the node configurationmodification region 22 by each node in the frame structure of FIG. 2.The node configuration modification region 22 is a region fortransmission by each node in the wireless bus 11 as required. The regionis used by a node that is either newly added to or deleted from thewireless bus 11, or modified in terms of its functions in the wirelessbus 11, in order to notify the hub station 12.

In FIG. 4, the node configuration modification notifying packet 40inserted into the node configuration modification region 22 includes amodification type 41 identifying the content of modification in the nodeconfiguration information, and node information 44 storing a uniqueidentifier 42 for each node and system parameters 43. The modificationtype 41 indicates three types of modification in the node configurationinformation, namely addition, deletion, and modification. The uniqueidentifier 42 in the node information 44 is a number that is registeredfor each device in advance, and there are no devices having identicalnumbers. The unique identifier 42 enables the individual devices to beidentified. The system parameters 43 store the functions of each node inthe wireless bus 11. In the wireless bus 11, the system parameters 43for each node are acquired from a managed node configuration informationtable (to be described later by referring to FIGS. 9 and 10) and used asa factor in making decisions during reconfiguration. The hub station 12,upon reception of the node configuration modification notifying packet40, updates its own node configuration information based on these itemsof information.

Referring back to FIG. 2, the communication quality information region23 is a region that is used for recognizing the communication pathcondition between individual nodes. The communication qualityinformation region 23 includes a region that is used for asynchronization sequence in a wireless bus regarding communicationquality information described in a prior art (JP Patent Publication(Unexamined Application) No. 11-215135). The node configurationinformation transmission region 24 is used by the hub station 12 intransmitting the node configuration information that has been updated ina previous frame to the nodes. The signal that is transmitted here isbroadcast. The data region 25 is a region that is used when transmittinga node configuration information request packet 50 (FIG. 5) from eachnode to the hub station, or when transmitting a node configurationinformation update packet 60 (FIG. 6) from the hub station to a specificnode. It is also used for transmitting multimedia data such as video orvoice data.

FIG. 5 shows the structure of the node configuration information requestpacket 50 inserted into the data region 25 in the frame structure ofFIG. 2 when a node requests retransmission from the hub station 12. Thenode configuration information request packet 50, which is used by anode that has failed to receive a broadcast signal in requestingretransmission from the hub station, has a node count (C_[Node]) 51. Thenode count (C_[Node]) 51 indicates a counter value retained by the nodethat has most recently been updated. By acquiring this nodeconfiguration information request packet 50 from the node, the hubstation 12 can recognize when was the last time a node configurationinformation table (to be described later by referring to FIG. 10)carried by the node was updated.

FIG. 6 shows the structure of the node configuration information updatepacket 60 that is broadcast by the hub station 12 using the nodeconfiguration information transmission region 24 in the frame structureof FIG. 2. In FIG. 6, the node configuration information update packet60 has a count (C) 61, a node number (#Node) 62, and node information 65for storing a unique identifier 63 for each node and system parameters64. The node number (#Node) 62 and the node information 65 constitutenode update information 66, in which a plurality of items of nodeconfiguration update information concerning updates in individual nodesare stored.

In the count (C) 61, a first counter value, carried by the hub station12 when an update occurs, is stored. In the node update information 66,node configuration update information concerning updates in individualnodes is stored. In each item of node configuration update information66, the node number (#Node) 62 of an updated node and the nodeinformation 44, which was described with reference to the nodeconfiguration modification notifying packet 40, are stored.

Upon reception of the node configuration information request packet 50,the hub station 12 broadcasts the node configuration information updatepacket 60 using the data region 25 shown in FIG. 2.

FIG. 7 shows node configuration information management blocks on thepart of the hub station for realizing the node configuration managementmethod according to the invention. In FIG. 7, numeral 71 designates acounter (C), numeral 72 a node configuration information table(management table on the part of the hub station), numeral 73 areceiver, numeral 74 a node configuration information detection means,numeral 75 a node configuration information modifying/extracting means,numeral 76 a node configuration information creating means, and 77 atransmitter.

The value in the counter (C) 71 is incremented by one when the nodeconfiguration information table as a whole in the hub station 12 hasbeen updated. The node configuration information table 72 is a table formanaging the node configuration information in the wireless bus 11. Thedetails of the node configuration information table 72 will be describedlater with reference to FIG. 9. The node configuration informationdetection means 74 has a function of detecting the node configurationmodification notifying packet 40 in the node configuration modificationregion and the node configuration information request packet 50 in thedata region in the signal frame received by the receiver 73.

If the node configuration information detection means 74 detects a nodeconfiguration modifying notification or a request for a retransmissionfrom a node, the node configuration information modifying/extractingmeans 75 accesses the node configuration information table 72 andmodifies or extracts information therein. When the node configurationinformation detection means 74 detects a retransmission request, thenode configuration information modifying/extracting means 75 extractsnode configuration information that must be retransmitted. Based on thisextracted node configuration information, the node configurationinformation creating means 76 creates a node configuration informationupdate packet 60. The frame start packet 30 that is required whenconfiguring a frame is also created here. The transmitter 77 has thefunction of transmitting a transmission signal created by the nodeconfiguration information creating means 76. The transmitter 77 has amemory device (queue) for the temporary storage of packets.

FIG. 8 shows the blocks for managing node configuration information onthe part of a node for realizing the node configuration managementmethod of the invention. In FIG. 8, numeral 81 designates a nodeconfiguration information table (management table on the part of anode), 82 a receiver, 83 a node configuration information detectingmeans, 84 a node configuration information modifying/extracting means,85 a node configuration information creating means, and 86 atransmitter.

The node configuration information table 81 is a table for managing nodeconfiguration information about the wireless bus 11 that is receivedfrom the hub station 12. The details of the node configurationinformation table 81 will be described later by referring to FIG. 10.The node configuration information detection means 83 has the functionof detecting the frame start packet 30 in the frame start region and thenode configuration information update packet 60 in the data region inthe signal frame received by the receiver 82.

When the node configuration information detection means 83 has receivedthe count (C) in the frame start packet 30 or the node configurationinformation update packet 60, the node configuration informationmodifying/extracting means 84 accesses the node configurationinformation table 81 to modify or extract information therein. If it isrevealed, as a result of the node configuration information detectionmeans 83 having acquired the count (C), that the information in thetable in the particular node is old, the node configuration informationcreating means 85 creates a node configuration information requestpacket 50 requesting retransmission of data. The node configurationinformation creating means 85 also creates a node configurationmodification notifying packet 40 notifying the hub station 12 of anymodification in node configuration. The transmitter 86 transmits atransmission signal created by the node configuration informationcreating means 85.

FIG. 9 shows in detail the node configuration information table 72possessed by the hub station 12. In the figure, the values in <> areexamples. As shown, in the node configuration information table 72 ofthe hub station 12, the current count (C) (first update timinginformation), a node number (#Node), the count (C_[Hub(#Node)]) for eachnode number upon updating (second update timing information), and nodeinformation for each node number are recorded.

The current count (C) is a first counter (counts: C) for managing thetiming of updating the management table as a whole. When the nodeconfiguration information or node information is updated, such as when anode is newly registered in or deleted from the wireless bus 11, or whenthe function of a node is modified, the count value is incremented byone. There are as many node numbers (#Node) prepared as the maximumnumber of nodes that can be stored in the wireless bus 11. The countupon updating (C_[Hub(#Node)]) is a second counter (counts: C_[Hub]) formanaging the timing of updating the node configuration information foreach node, and it is associated with a node number (#Node). In thisregion, the count (C) that is present when the node configurationinformation or the node information associated with a particular nodenumber has been updated is stored. The node information (uniqueidentifier+system parameters) is a region in which the hub station 12secures node information that has been notified via the nodeconfiguration modification notification region. Based on this nodeinformation, the hub station 12 overwrites the node configurationinformation table 72.

FIG. 10 shows the details of the node configuration information table 81possessed by a node. In the figure, values in <> are examples. As shown,in the node configuration information table 81 for each node, the count(C_[Node]) upon updating, node number (#Node), and node information foreach node are recorded.

The count (C_[Node]) upon updating is where the current count (C) that anode acquires when it receives the node configuration information updatepacket 60 from the hub station 12 is stored. Thus, this count (C)indicates when the last update was. The contents of the node number(#Node) and node information are the same as those of the node number(#Node) in the node configuration table 72 on the part of the hubstation 12 as described above. The node receives the node configurationinformation update packet 60 transmitted from the hub station 12 andacquires updated node configuration information, and then overwrites theupdated portion.

Hereafter, the operation of the above-described method of managing nodeconfiguration information will be described in detail. First, thesequence of synchronizing node configuration information in the wirelessbus 11 will be described. FIG. 11 shows the node configurationinformation management sequence starting from the time when the nodeconfiguration is updated up to the time when the updated configurationis transmitted to all of the nodes in the wireless bus 11.

<Node Information Notifying Process (1)>

When a node is newly registered in or deleted from the wireless bus 11,or when the system parameters in the wireless bus 11 has been modified,for example, the relevant node initially transmits a node configurationmodification notifying packet 40 to the hub station 12 via the nodeconfiguration modification region 22. The new registration or deletionof a node from the wireless bus 11, modification of node functions, ormodification of the system parameters in the wireless bus 11, forexample, are carried out by the node notifying the hub station 12.

<Update Process on the Part of the Hub Station 12 (2)>

Upon reception of the node configuration modification notifying packet40, the hub station 12 updates the node configuration information table72 in the hub station 12 based on the received packet 40.

<Node Configuration Information Notifying Process (3)>

In the next frame, the hub station 12 transmits a frame start packet 30in order to begin a frame start region 21. Each node in the wireless bus11 receives the frame start packet 30 and identifies the head positionof the frame. If node configuration update information exists, the hubstation broadcasts a node configuration information update packet 60 toall of the nodes in a node configuration information transmission region24.

<Update Process on the Part of a Node (4)>

Each node acquires the count (C) transmitted from the hub station 12 inthe frame start region 21, compares it with the count (C_[Node]) in itsown table (node configuration information table 81), and makes adecision in the following process.

If the count (C_[Node]) of its own corresponds to the acquired count(C), the node determines that its own node configuration informationtable 81 is the latest node configuration information, and the processcomes to an end. If the count (C_[Node]) of its own is one count earlierthan the acquired count (C), the node determines that the nodeconfiguration information has been updated in the hub station 12. Then,the node acquires a node configuration information update packet 60 thatshould be transmitted from the hub station 12 in the subsequent nodeconfiguration information transmission region 24. Based on that packet,the node overwrites its own node configuration information table 81.

If the node configuration information update packet 60 is not received,or if the comparison of counts shows that count (C_[Node]) in the nodeis two or more counts earlier than the acquired count (C), the nodemakes a retransmission request to the hub station 12 in the data region.Based on the retransmitted packet, the node updates the nodeconfiguration information table 81.

<Retransmission Process (5)>

This retransmission process indicates the sequence of a node requestingthe hub station 12 for retransmission in case the node failed to receivethe node configuration information update packet 60 that was broadcast.The hub station 12 receives a node configuration information requestpacket 50 from the particular node and acquires the counter value in thenode, and makes a decision as to up to which point of the nodeconfiguration information should be transmitted. Then, the hub station12 transmits the information to the requesting node in a nodeconfiguration information update packet 60.

Hereafter, the individual process steps 1 to 5 illustrated in FIG. 11will be described by referring to a flowchart.

<Sequence of the Node Information Modification Notifying Process (1)Carried Out on the Part of a Node>

FIG. 12 shows a flowchart of the sequence of the node informationnotification process (1) carried out on the part of a node in the nodeconfiguration information management sequence of FIG. 11. In the figure,S indicates each step of the flow.

In step S11, the node makes a decision as to whether there is newregistration in the wireless bus 11, deletion from the wireless bus 11,or modification in the node's system parameters in the wireless bus 11.If there is no modification, the sequence comes to an end. If there is amodification, a node configuration modification notifying packet 40 isprepared in which the type of modification (addition, deletion, ormodification) and node information are inserted in accordance with theformat of the node configuration modification notifying packet 40 (seeFIG. 4) in step S12. The node transmits the thus prepared nodeconfiguration modification notifying packet 40 to the hub station 12 instep S13, and the process comes to an end.

<Sequence of the Node Configuration Updating Process (2) Carried Out onthe Part of the Hub Station 12>

FIG. 13 shows a flowchart of the node configuration updating process (2)sequence carried out on the part of the hub station 12 in the nodeconfiguration information management sequence of FIG. 11.

In step S21, the hub station 12 determines whether or not it hasreceived the node configuration modification notifying packet 40. Ifnot, the process comes to an end. If the hub station 12 has received thenode configuration modification notifying packet 40, the hub station 12updates its own node configuration information table 72 in step S22 andoverwrites the current count (C) on the count (C_[Hub(#Node)]) whereupdated. Then, in step S23, the count (C) is incremented by one, a nodeconfiguration information update packet 60 is stored in a transmissionqueue in step S24 for transmission in the node update informationtransmission region of the subsequent frame, and then the process comesto an end.

<Sequence of Frame Start Region 21 Process (3) on the Part of the HubStation 12>

FIG. 14 shows a flowchart of the sequence of the frame start region 21process (3) carried out on the part of the hub station 12 in the nodeconfiguration information management sequence of FIG. 11.

In step S31, the hub station 12 transmits a head position detectionsignal. By receiving this signal, each node in the wireless bus 11identifies the head position of the frame. In step S32, the hub station12 transmits a size notifying signal. By receiving this signal, eachnode in the wireless bus 11 identifies the subsequent frameconfiguration. Then, in step S33, the hub station 12 transmits a count(C). The processes up to this point are carried out in the frame startregion.

Then, the sequence enters the node configuration informationtransmission region, and in step S34, it is determined whether or notdata exists in the node configuration information transmission queue. Ifdata exists in the transmission queue, the hub station 12 broadcasts thenode configuration information update packet 60 to all of the nodes instep S35, and the process comes to an end. If there is no data in thetransmission queue, the process comes to an end at that point.

<Sequence of the Node Configuration Information Updating Process (4) onthe Part of a Node>

FIG. 15 shows a flowchart of the sequence of the node configurationinformation updating process (4) carried out on the part of a node inthe node configuration information management sequence of FIG. 11.

In step S41, a node acquires the count (C) transmitted from the hubstation 12 in the frame start region 21. In step S42, the node comparesthe count with its own count (C_[Node]). If the counts correspond, thenode determines that its own node configuration information table 81 isthe latest one, and the sequence comes to an end.

If the counts do not correspond, the node determines whether or not itsown count (C_[Node]) is one count earlier than the acquired count instep S43. If its own count (C_[Node]) is one count earlier than theacquired count, the node determines that the node configurationinformation has been updated on the part of the hub station 12, and itthen determines in step S44 whether a broadcast signal has been receivedin the subsequent node configuration information control region. If itis determined in step S43 that the count (C_[Node]) of the node is notone count earlier than the acquired count, the sequence proceeds to stepS46. The processes up to this point are carried out in the frame startregion.

If the broadcast signal is received in step S44, the node acquires anode configuration information update packet 60 in step S45 and updatesits own table (node configuration information table 81) based on thisinformation, and the sequence comes to an end. This process is carriedout in the node configuration information transmission region.

If the count of the node (C_[Node]) is two or more counts earlier thanthe acquired count (“NO” in step S43), or if the broadcast signal is notreceived, the node makes a node configuration information retransmissionrequest in the data region in step S46. Then, in step S47, the nodedetermines whether or not the node configuration information updatepacket 60 has been received. If not, the sequence returns to step S46 torepeat the retransmission request.

Upon reception of the node configuration information update packet 60from the hub station 12, the node updates its own node configurationinformation table 81 based on the node configuration information updatepacket 60 in step S48, overwrites its own count (C_[Node]) with thecurrent count (C), and then the process comes to an end.

<Retransmission Process (5) Sequence on the Part of the Hub Station 12>

FIG. 16 shows a flowchart of the sequence of the retransmission process(5) carried out on the part of the hub station 12 in the nodeconfiguration information management sequence of FIG. 11.

In step S51, the hub station 12, having received the node configurationinformation request packet 50 in step S51, acquires the count (C_[Node])from the packet and makes the node number (#Node) zero in step S52.Then, in step S53, the hub station 12 compares the acquired count(C_[Node]) with the count (C_[Hub(#Node)]) stored in the nodeconfiguration information table 72 stored in the hub station 12 on anode-by-node basis. Based on this comparison of counts, it is determinedwhether the information possessed by the node is older than thatpossessed by the hub station 12.

If the acquired count (C_[Node]) is older than the count (C_[Node]) inthe table of the hub station 12, the hub station 12, deciding that itmust transmit the node information concerning the node, inserts the nodenumber (#Node) and node information into the node configurationinformation update packet 60 in step 54. In step S55, it is determinedwhether the node number (#Node) has exceeded the maximum node number. Ifnot, the node number (#Node) is incremented for the next node (#Node++)in step S56 for carrying out a retransmission process for the next node,and the sequence returns to step S53, where the above operation isperformed for all of the nodes. When the node number (#Node) hasexceeded the maximum node number, it is determined that the operationhas been completed for all of the registered nodes. Then, the currentcount (C) is added to the packet and the node configuration informationpacket is transmitted in the final step S57, thus ending the process.

In order to ensure the completeness of the data or to simplify it, allof the node configuration information currently possessed by the hubstation may be transmitted without carrying out the above sequence.

In sequences (1) to (5), if the various packets cannot be transmitted inthe same frame, such as when the node configuration information size islarge, the transmission may start after waiting for the beginning of therelevant region in the next frame.

As described above, in accordance with the node configurationinformation management method according to the first embodiment, theframe structure 20 has the frame start region 21, node configurationmodification region 22, communication quality information region 23,node configuration information transmission region 24, and data region25. When a change (new registration or deletion of a node, ormodification of the node functions) occurs in the node information inthe wireless bus 11, the node notifies the hub station 12 of themodification by means of the modification notifying packet. Thus, thereis no need to notify the hub station 12 of node configurationinformation in each frame, enabling communication without redundancy.

According to the present node configuration information managementmethod, basically:

-   (1) The nodes 13 to 16 and the hub station 12 store the node    configuration information for each node in the node configuration    information tables 72 and 81, and the hub station 12 has the    counter (C) 71 for managing the updating of the node configuration    information table 72 as a whole, and transmits the count (C) (first    update timing information) periodically (in each frame in the    embodiment);-   (2) The hub station 12, upon reception of a notification of change    in the node configuration from a node, updates the node    configuration information table 81 in the hub station 12, and    broadcasts the update information to all of the nodes in the    wireless bus 11; and-   (3) Each node receives the update information from the hub station    12 and updates its own node configuration information table 81. The    node further receives the count that is transmitted in each frame    and determines whether or not there is any updating on the part of    the hub station 12. If necessary, the node requests the    retransmission of differential information with respect to its own    node configuration information table 81, and updates its own node    configuration information table 81.

Particularly, the hub station 12 has a first counter (count: C) formanaging the update timing for the node configuration information table72 as a whole and, further, a second counter (count: C_[Hub]) formanaging the update timing for the node configuration information foreach node.

The hub station 12 transmits the current count (C) to all of the nodesin the wireless bus 11 in each frame, thus notifying them of the currentupdate situation. Each of the nodes has a region (C_[Node]) for storingthe first count (C), acquires the first count (C) transmitted from thehub station 12 in each frame, and determines whether or not the node issynchronized with the hub station 12. Thus, the hub station 12 cantransmit only a portion of the information in the node configurationinformation tables 72 and 81 that has been modified in the node,reducing the amount of data transmitted.

Further, the hub station 12 broadcasts the node configuration updateinformation, so that there is no need for the hub station 12 to wait foran Ack from the nodes. Even if a node has failed to receive the nodeconfiguration update information, the node can detect the failure byacquiring the count (C) in the subsequent frame. By requesting theretransmission of the node configuration information from the hubstation 12 on a node-by-node basis, synchronization between the node andthe hub station can be maintained.

According to the present embodiment, the hub station transmits only anecessary portion of the node configuration information to each of thenodes in the wireless bus 11, so that the node configuration informationcan be synchronized between the hub station 12 and the nodes efficientlyand reliably.

The node configuration information management method according to thefirst embodiment requires at least two frames before the nodeconfiguration information table 81 in each of the nodes in the wirelessbus can be updated following the notification of node configurationmodification. It is possible that some of the data that is transmittedduring that time becomes invalid. Further, as the decision as to whetheror not the node configuration information tables in the wireless bus 11have been updated is made by individual nodes, the hub station 12 cannotrecognize the update situation on the part of the nodes. In thefollowing, a second embodiment that can solve these problems will bedescribed.

SECOND EMBODIMEMT

The configuration of the terminals and the hub station in a wireless busaccording to this embodiment is similar to that shown in FIG. 1.

FIG. 17 shows the structure of a frame that is transmitted and receivedin the wireless bus according to the second embodiment, the framestructure corresponding to FIG. 2.

As shown in FIG. 17, a wireless signal with a frame structure 90 isdivided into a frame start region 91, a node configuration informationmodification region 92, a node configuration information transmissionregion 93, a communication quality information region 94, and a dataregion 95. The hub station 12 indicates the start of a frame by usingthe start region 91 in each frame.

FIG. 18 shows a frame start packet 100 in detail, which the hub station12 inserts into the frame start region 91 in the frame structure of FIG.17. In FIG. 18, the frame start region 91 has a head position detectionregion 101 for storing a head position detection signal, and a sizenotifying region 102 for storing a size notifying signal. The headposition detection region 101 is used for notifying each node in thewireless bus 11 of the start of a frame. Each node in the wireless bus11 identifies the frame start position by receiving this head positiondetecting signal. The size notifying region 102 is used for transmittingthe size of each of the variable-size regions in the frame that aresubsequently transmitted. Based on this size notifying signal, each nodein the wireless bus can identify the subsequent frame structure.

FIG. 19 shows the structure of a node configuration modificationnotifying packet 110 in detail, which a node inserts into the nodeconfiguration information modification region 92 in the frame structureof FIG. 17. The node configuration information modification region 92 isused for transmission by each node in the wireless bus 11 as necessary.When a node is newly added to the wireless bus 11, when a node isdeleted from the wireless bus 11, or when the function of a node in thewireless bus 11 is modified, the relevant node notifies the hub station12 of the modification using the node configuration informationmodification region 92.

In FIG. 19, the node configuration modification notifying packet 110inserted into the node configuration information modification region 92includes a modification type 111 for identifying the content of themodification in the node configuration information, and a nodeinformation 114 for storing a unique identifier 112 and systemparameters 113 for each node. The modification type 111 enables theidentification of three kinds of modification, namely addition,deletion, and modification in the node configuration information.

The unique identifier 112 is a number that is registered for each devicein advance. No devices have identical numbers. The unique identifier 112enables the individual devices to be identified. The system parameters113 stores the function of each node in the wireless bus 11. Thewireless bus 11 acquires the system parameters 113 of each node on thebasis of a managed node configuration information table (to be describedlater by referring to FIGS. 24 and 25) and uses it as a factor in makingdecisions during reconfiguration.

The hub station 12, upon reception of the node configurationmodification notifying packet 110, updates its own node configurationinformation based on these items of information.

FIG. 20 shows the structure of a node configuration information updatepacket 120 that is inserted into the data region 95 in the framestructure of FIG. 17 when the hub station 12 re-transmits to a node. InFIG. 20, the node configuration information update packet 120 includes acount (C) 121, a node number (#Node) 122, and node information 125. Thenode information 125 stores a unique identifier 123 for each node andsystem parameters 124. The node number (#Node) 122 and the nodeinformation 125 constitute node update information 126, in which aplurality of items of node configuration update information updated inthe individual nodes are stored.

In the count (C) 121, the value in the first counter possessed by thehub station 12 upon updating is stored. In the node update information126, the node configuration update information updated in each node isstored. In each item of node configuration update information 126, thenode number (#Node) 122 of an updated node and the node information 114described with reference to the node configuration modificationnotifying packet 110 are stored. The node configuration informationupdate packet 120 is used by the hub station 12 when it retransmits inresponse to the node configuration information request packet (FIG. 5).

Referring back to FIG. 17, the node configuration informationtransmission region 93 is a region used by the hub station 12 intransmitting the node configuration information updated in a previousframe to a node. The signal transmitted here is broadcast. Thisbroadcast node configuration information update packet has the samestructure as that of the node configuration information update packet120. The communication quality information region 94 is used forrecognizing the communication path conditions between the individualnodes.

FIG. 21 shows the structure of the data region 95 in the frame shown inFIG. 17. In FIG. 21, the data region 95 includes a count (C_[Node])transmission region 131 for each node in the wireless bus 11, and a dataregion 132 including the operation of the transmission of the nodeconfiguration information update packet 120 for a node that is notsynchronized and for the transmission and reception of normal data.

The count transmission region 131 is used for confirming whether or noteach node in the wireless bus 11 is synchronized with the nodeconfiguration information table in the hub station 12. For each wirelessframe, each node reports its own current count (C_[Node]) to the hubstation 12. The hub station 12 acquires the count (C_[Node]) and thenupdates its own node configuration information table. By comparing thecount (C_[Node]) of each node with the current count (C), the hubstation 12 confirms the update situations concerning all of the nodesand determines whether or not the nodes in the wireless bus 11 aresynchronized. The data region 132 is a region that is used by the hubstation 12 in transmitting the node configuration information updatepacket 120, as well as multimedia data such as video or voice data, to aparticular node.

FIG. 22 shows node configuration information management blocks on thepart of the hub station for realizing the node configuration managementmethod according to the present embodiment, the figure corresponding toFIG. 7. In FIG. 22, numeral 141 designates a counter (C), 142 a nodeconfiguration information table (management table on the part of the hubstation), 143 a receiver, 144 a node configuration information detectionmeans, 145 a node configuration information modifying/extracting means,146 a node configuration information creating means, and 147 atransmitter.

The value in the counter (C) 141 is incremented by one when the nodeconfiguration information table in the hub station 12 is updated as awhole. The node configuration information table 142 is a table formanaging the node configuration information in the wireless bus 11. Thedetails of the node configuration information table 142 will bedescribed later by referring to FIG. 24. The node configurationinformation detection means 144 has the function of detecting the nodeconfiguration modification notifying packet 110 in the nodeconfiguration modification region, the count transmission region 131 inthe data region, and the node configuration information update packet120 in the signal frame received by the receiver 143. The nodeconfiguration information modifying/extracting means 145, when the nodeconfiguration information detection means 144 detects a notification ofnode configuration modification, accesses the node configurationinformation table 142 and then modifies or extracts information in thetable 142.

The node configuration information creating means 146 creates a nodeconfiguration information update packet 120 for a node that the hubstation 12 has decided requires retransmission. It also creates a framestart packet 100 that is necessary when configuring a frame. Thetransmitter 147 has the function of transmitting a transmission signalcreated by the node configuration information creating means 146. Thetransmitter 147 includes a memory device (queue) for the temporarystorage of packets.

FIG. 23 shows the node configuration information management blocks onthe part of a node for realizing the node configuration managementmethod according to the present embodiment, the figure corresponding toFIG. 8. In FIG. 23, numeral 151 designates a node configurationinformation table (management table on the part of a node), 152 areceiver, 153 a node configuration information detection means, 154 anode configuration information modifying/extracting means, 155 a nodeconfiguration information creating means, and 156 a transmitter.

The node configuration information table 151 is a table for managing thenode configuration information in the wireless bus 11 that is receivedfrom the hub station 12. The details of the node configurationinformation table 151 will be described later by referring to FIG. 25.The node configuration information detection means 153 has the functionof detecting the frame start packet 100 in the frame start region andthe node configuration information update packet 120 in the data regionin the signal frame received by the receiver 152. The node configurationinformation modifying/extracting means 154, when the node configurationinformation detection means 153 receives the node configurationinformation update packet 120, accesses the node configurationinformation table 151 and then modifies or extracts information in thetable 151. It also has the function of extracting the count (C_[Node])of the node from the node configuration information table 151.

The node configuration information creating means 155 has the functionof transmitting, in each frame, the count (C_[Node]) of the node in thenode configuration information table 151 that is extracted by the nodeconfiguration information modifying/extracting means 153. It alsocreates the node configuration modification notifying packet 110 fornotifying the hub station 12 of any modifications in the nodeconfiguration. The transmitter 156 has the function of transmitting atransmission signal created by the node configuration informationcreating means 155. The transmitter 156 has a memory device (queue) forthe temporary storage of packets.

FIG. 24 shows in detail the node configuration information table 142possessed by the hub station 12. In the figure, values in <> areexamples. As shown, the node configuration information table 142 in thehub station records the current count (C), the node number (#Node), thecount (C_[Hub(#Node)]) upon updating for each node number, the count(C_[Hub(#Node)]) on the part of a node for each node number, and nodeinformation for each node number.

The value of the current count (C) is incremented by one when the nodeconfiguration information or the node information is updated, such aswhen a node is newly registered in the wireless bus 11, when a node isdeleted, or when the function of a node is modified. As many nodenumbers (#Node) are provided as the maximum number of nodes that can bestored in the wireless bus 11. The counts (C_[Hub(#Node)]) at updatingare associated with node numbers. In this region, the count (C) thatexists when the node configuration information or node informationassociated with a particular number is updated is stored. As many nodecounts (C_[Node(#Node)]) are provided as there are nodes. In thisregion, the count for each node in the wireless bus 11 that has beentransmitted in the count transmission region 131 in each frame isstored. The node information (unique identifier +system parameters) is aregion where the hub station 12 secures the node information that hasbeen transmitted from a node in the above-mentioned node configurationmodification notifying region. Based on this node information, the hubstation 12 overwrites the node configuration information table 142.

FIG. 25 shows in detail the structure of the node configurationinformation table 151 possessed by a node. In the figure, values in <>are examples. As shown in FIG. 25, the node configuration informationtable 151 for each node stores the count (C_[Node]) upon updating, thenode number (#Node), and the node information for each node.

The count (C_[Node]) upon updating is where the current count (C) thatthe node acquires when receiving the node configuration informationupdate packet 120 from the hub station 12 is stored. The count (C)therefore indicates when the last update took place. The contents of thenode number (#Node) and the node information are the same as those ofthe node number (#Node) in the node configuration table 142 on the partof the hub station 12. The node receives the node configurationinformation update packet 120 transmitted from the hub station 12,acquires the updated node configuration information, and then overwritesthe updated portion.

Hereafter, the operation of the node configuration informationmanagement method described above will be described in more detail.

First, the sequence for synchronizing node configuration information inthe wireless bus 11 will be described. FIG. 26 illustrates the nodeconfiguration information managing sequence, which corresponds to thenode configuration information managing sequence illustrated in FIG. 11.

<Frame Start Packet Transmission Process>

In the frame start region 91, the hub station 12 transmits a headposition detection signal 101 and a size notification 102 using theframe start packet 100 shown in FIG. 18.

<Frame Start Packet Reception Process>

A node that has received the frame start packet 100 acquires the headposition detection signal 101, identifies the head position, andidentifies the subsequent frame structure based on the size notifyingsignal 102.

<Node Information Notifying Process (6)>

If there is a modification in the configuration information in a node inthe wireless bus 11, the node transmits the node configurationmodification notifying packet 110 to the hub station 12 in the nodeconfiguration information modification region 92.

<Node Configuration Update Process (7)>

Upon reception of the node configuration modification packet 110, thehub station 12 updates its own node configuration information table 142.Then, the hub station 12 broadcasts the node configuration informationupdate packet 120 to which the current count (C) is attached to all ofthe nodes in the wireless bus 11 in the node configuration informationtransmission region 93.

<Update Procedure (8)>

A node that has received the node configuration information updatepacket 120 acquires the current count (C) of the hub station 12 and thenode update information, and then updates its own node configurationinformation table 151. In the count transmission region 131, the count(C_[Node]) carried by the node is transmitted to the hub station 12,thus notifying the hub station 12 of the update situation in the table(node configuration information table 151) of the node.

<Node Configuration Information Synchronizing Process (9)>

Having acquired the count (C_[Node]) of each of the nodes in thewireless bus 11 and updated the table (node configuration informationtable 142) via the count transmission region 131, the hub station 12compares the acquired counts with its own current count (C) to determinewhether or not all of the tables have been updated. If there is a tablethat has not been updated, the hub station 12 carries out aretransmission process (10) using the data region 95. In thisretransmission process (10), the node configuration information updatepacket 120 is transmitted to the node that is not updated. The node thathas received the node configuration information update packet 120performs the update procedure (8). Specifically, the node overwrites thenode configuration information table 151 based on the count (C) and thenode information in the packet.

Hereafter, each of the process sequences (6) to (10) shown in FIG. 26will be described by referring to a flowchart.

<Sequence of the Node Information Modification Notifying Process (6) onthe Part of a Node>

FIG. 27 shows a flowchart of the node information notifying process (6)sequence on the part of a node in the node configuration informationmanaging sequence shown in FIG. 26.

Initially, in step S61, the node determines if it is newly registered ordeleted, or if there is any modification in the system parameters. Ifthere is no modification, the process comes to an end. If there is amodification, a node configuration modification notifying packet 110 iscreated in step S62. After adding the type of modification(registration, deletion, or modification), unique identifier, and systemparameters, the node configuration modification notifying packet 110 istransmitted to the hub station 12 in step S63, and then the processcomes to an end.

<Sequence of the Node Configuration Update Process (7) on the Part ofthe Hub Station 12>

FIG. 28 shows a flowchart of the node configuration update process (7)sequence on the part of the hub station 12 in the node configurationinformation managing sequence shown in FIG. 26.

In step S71, the hub station 12 determines whether or not it hasreceived the node configuration modification notifying packet 110. Ifnot, the process comes to an end. If it has received the nodeconfiguration modification notifying packet 110, it updates its own nodeconfiguration information table 142 in the hub station 12 in step S72,and overwrites the current count (C) on the count (C_[Hub(#Node)]) whereupdated. Thereafter, the hub station 12 increments the count (C) by onein step S73, creates a node configuration information update packet 120in the node update information transmission region in step S74, andbroadcasts it to all of the nodes in the wireless bus 11, before theprocess comes to an end.

<Sequence of the Update Procedure (8) on the Part of a Node>

FIG. 29 shows a flowchart of the sequence of the update procedure (8) onthe part of a node in the node configuration information managingsequence shown in FIG. 26.

In step S81, the node receives the node configuration information updatepacket 120 from the hub station 12. In step S82, the node acquires thecount (C) and the node update information, and then overwrites its ownnode configuration information table 151 to complete the process.

<Sequence of the Node Configuration Information Synchronizing Process(9) on the Part of the Hub Station 12>

FIG. 30 shows a flowchart of the sequence of the node configurationinformation synchronizing process (9) on the part of the hub station 12in the node configuration information managing sequence shown in FIG.26.

In step S91, the hub station 12 acquires the count in each of the nodesin the wireless bus 11 that was transmitted in the count transmissionregion, and then updates the counts (C_[Node]) in its own nodeconfiguration information table 142. Thereafter the hub station 12 makesthe node number (#Node) zero in step S92.

In step S93, the node count (C_[Node]) and the current count (C) in thenode configuration information table are compared in order to determinewhether the table in the node has been updated. Based on this comparisonof the counts, a decision is made as to the advisability ofretransmission to each node starting from the node number zero(#Node←0). When the table of the node is up to date, the process goes tostep S95 to end the process on this particular node. If the table of thenode is not up to date, a retransmission process (10) is performed instep S94, before the process on this particular node comes to an end.The details of the retransmission process (10) will be described laterby referring to FIG. 31.

In step S95, it is determined whether the node number (#Node) hasexceeded the maximum node number. If not, the node number (#Node) isincremented to the next node (#Node++) in step S96 for carrying out aretransmission process for the next node. The sequence then returns tostep S93, from which the above operation is repeated for all of thenodes. When the node number (#Node) has exceeded the maximum nodenumber, it is decided that the operation has been performed on all ofthe registered nodes. Then, the data that was stored in the queue in theretransmission process (in step S94) is transmitted to the node in needof retransmission in step S97, thus concluding the present process.

<Sequence of the Retransmission Process (10) on the Part of the HubStation 12>

FIG. 31 shows a flowchart of the sequence of the retransmission process(10) on the part of the hub station 12 in the node configurationinformation managing sequence shown in FIG. 26.

Initially, in step S101, the hub station 12 acquires the count(C_[Node]) of the node in the node configuration information table 142.In step S102, the hub station 12 makes the node number (#Node) zero.Then, in step 103, the hub station 12 compares the acquired count(C_[Node]) with the count (C_[Hub(#Node)]) stored in its own nodeconfiguration information table 142 on a node-by-node basis. Based onthis comparison of the counts, it is determined whether the informationpossessed by the node is older than that owned by the hub station 12.

If the acquired count (C_[Node]) of the node is older than the count(C_[Node]) in the table of the hub station 12, the hub station, decidingthat the node information concerning the particular node must betransmitted, inserts this node (#Node) and the node information into thenode configuration information update packet 120 in step S104 Thesequence then proceeds to step S105. If the decision in step S103 isnegative, the sequence goes to step S105.

In step S105, it is determined whether the node number (#Node) hasexceeded the maximum node number. If not, the node number (#Node) isincremented for the next node (#Node++) for carrying out aretransmission process therefor. The sequence then returns to step S103,and the above operation is performed for all of the nodes.

When the node number (#Node) exceeds the maximum node number, it isdecided that the operation has been performed on all of the registerednodes, and the current count (C) is added to the packet in the finalstep S107. After the node configuration information packet is stored inthe transmission queue, the process comes to an end.

In order to ensure the completeness of or to simplify the data, allitems of the node configuration information currently owned by the hubstation may be transmitted without carrying out the above sequence.

If the various packets cannot be transmitted in the same frame in thesequences (1) to (10) because the node configuration information size islarge, for example, the transmission may begin after waiting for thebeginning of relevant regions in the next frame.

Thus, in accordance with the node configuration information managementmethod in the second embodiment, when the node configuration informationtable 142 in the hub station 12 is updated as a result of a change inthe node configuration in the wireless bus 11, the hub station 12broadcasts the update information in the node configuration informationtable 142 and update timing to all of the nodes in the wireless bus 11.Each node in the wireless bus 11 receives the update information andthen updates its own node configuration information table 151 includingthe update timing and the node configuration information. Each node inthe wireless bus 11 notifies the hub station 12 of the update timing.Based on the reported update timing, the hub station 12 recognizes theupdate situation in the node configuration information table 151 in eachnode. If there is a node that is not updated, the hub station 12retransmits the update information to that node. In this manner, even anode that failed to receive the broadcast signal can maintainsynchronization with the hub station 12 between the node configurationinformation tables 142 and 151.

The modification notifying sequence on the part of the nodes is the sameas that in Embodiment 1. Thus, the hub station 12, in response to amodification notification from a node, broadcasts the node configurationinformation update packet 120 including the current count (C) and theupdate information in the same frame to all of the nodes in the wirelessbus 11.

Each node receives the broadcast signal and then updates its own nodeconfiguration information table 151. The node then notifies the hubstation 12 of the current count in the node in each frame. The hubstation 12 acquires the count from each of the nodes in the wireless bus11, and compares it (C_[Node]) with the current count (C) in the nodeconfiguration information table 142. The hub station 12 does nothingwith respect to a node that has the same count. When the counts aredifferent, the hub station 12 decides that the node is out ofsynchronization, and creates differential data corresponding to thenode's count (C_[Node]). The hub station 12 then transmits a nodeconfiguration information update packet 120 including the current count(C) to the particular node. The node that has received the update dataupdates its own node configuration information table 151, so that it issynchronized with the node configuration information table 142 managedby the hub station 12.

In accordance with the present embodiment, the node configurationinformation table 142 managed by the hub station 12 can be synchronizedwith all of the nodes in the wireless bus 11 within a minimum one frame,so that no invalid data is created during synchronization. Further,because the hub station 12 can recognize the update situation in eachnode in the wireless bus 11, the hub station can decide whether or not aretransmission is necessary for any of the nodes.

INDUSTRIAL APPLICABILITY

Thus, in accordance with the invention, the hub station centrallymanages the node configuration information in a wireless bus comprisingthe hub station and a plurality of nodes, so that the hub station canshare the latest node configuration information with all of the nodes.

Further, in accordance with the invention, the hub station centrallymanages the node configuration information in a wireless bus comprisingthe hub station and a plurality of nodes, so that the hub station canshare the latest node configuration information with all of the nodes inthe wireless bus within the shortest frame.

1. A method of managing the node configuration in a wireless networkcomprising a hub station and a plurality of nodes, wherein the hubstation comprises a hub station management table for managing uniqueinformation about each of the nodes, wherein the updating of the hubstation management table is managed by first update timing informationthat is transmitted to all of the nodes periodically, wherein if the hubstation management table is modified, modification information istransmitted to all of the nodes together with the first update timinginformation, wherein each node has a node management table for managingthe unique information about the node, wherein the node receives thefirst update timing information and the update information, comparesfirst update timing information in its own management table with thefirst update timing information transmitted from the hub station, andrewrites its own management table based on the update information if itsown update timing information is older.
 2. A method of managing the nodeconfiguration in a wireless network comprising a hub station and aplurality of nodes, wherein the hub station has a hub station managementtable for managing unique information about each of the nodes, whereinupdating of the hub station management table is managed based on firstupdate timing information that is transmitted to all of the nodesperiodically, wherein each node has a node management table for managingthe unique information about the node, wherein the node receives thefirst update timing information and compares first update timinginformation in its own management table with the first update timinginformation transmitted from the hub station, wherein the node requeststhe transmission of the unique information data if its own update timinginformation is old, and rewrites its own management table based on theunique information data transmitted from the hub station in response tothe request.
 3. The node configuration management method according toclaim 2, wherein the unique information data transmitted from the hubstation in response to the request from the node for the transmission ofthe unique information data is differential data including only thatdata in the unique information which relates to a node that has beenadded, modified, or deleted subsequent to the update timing informationcarried by the node.
 4. The node configuration management methodaccording to claim 2, wherein the first update timing information issequentially updated, wherein, if the first update timing information ofthe node is older than the first update timing information transmittedfrom the hub station by two or more, the node requests the hub station,together with the update timing information of its own, to transmit therelevant differential data.
 5. A method of managing the nodeconfiguration in a wireless network comprising a hub station and aplurality of nodes, wherein the hub station has a hub station managementtable for managing unique information about each node, wherein updatingof the hub station management table is managed based on first updatetiming information, wherein each node has a node management table formanaging the unique information about each node, wherein the updating ofthe node management table is managed based on the first update timinginformation, the node periodically transmitting the first update timinginformation that it manages to the hub station, wherein the hub stationcompares its own first update timing information with the first updatetiming information transmitted from each node periodically, the hubstation creating the unique information data if the two items ofinformation are different and transmitting it to the corresponding node,wherein the node rewrites its own management table based on the datatransmitted from the hub station.
 6. The node configuration managementmethod according to claim 5, wherein the hub station compares the firstupdate timing information periodically transmitted from each node withits own first update timing information, and if there is a difference,the hub station creates unique information differential datacorresponding to the difference and transmits it to the relevant node.7. The node configuration management method according to claim 5,wherein the hub station periodically transmits the first update timinginformation to all of the nodes and, if the management table ismodified, the hub station transmits modification information to all ofthe nodes together with the first update timing information.
 8. The nodeconfiguration management method according to claim 5, wherein a framestructure for wireless transmission includes a region for transmittingthe unique information about each node, a region for the hub station totransmit modified portion of the unique information to all of the nodes,and a data region for transmitting and receiving normal data, whereinthe nodes make retransmission requests to the hub station individuallyby using the data region, the hub station transmitting differential datain response to the retransmission request using the data region.
 9. Thenode configuration management method according to claim 1 or 4, whereinthe hub station manages updating of the unique information about eachnode based on second update timing information in the hub stationmanagement table, wherein the hub station compares the first updatetiming information transmitted from each node with the second updatetiming information of the relevant node in order to select differentialdata.
 10. The node configuration management method according to claim 1or 2, wherein a frame structure for wireless communication includes aregion for transmitting the first update timing information managed bythe hub station to all of the nodes, a region for transmitting theunique information about each node, a region for the hub station totransmit modified portion of the unique information to all of the nodes,and a data region for transmitting and receiving normal data, whereineach node makes a retransmission request to the hub station individuallyusing the data region, the hub station transmitting differential data inresponse to the retransmission request using the data region.
 11. Awireless network system comprising a hub station and a plurality ofnodes, wherein the hub station comprises a hub station management tablefor managing unique information about each node based on first updatetiming information, a detection means for detecting a modification inthe node configuration, an update means for updating the hub stationmanagement table in accordance with the result of detection by thedetection means, and a transmitter for transmitting, if there is amodification in the hub station management table, modificationinformation to all of the nodes together with the first update timinginformation, as well as transmitting the first update timing informationto all of the nodes periodically, wherein each node comprises a nodemanagement table for managing the unique information about the nodebased on the first update timing information, a receiver for receivingthe first update timing information, and an update means for comparingthe first update timing information in the node management table of thenode with the first update timing information transmitted from the hubstation and for updating, if the update timing information of the nodeis old, its own node management table based on the modificationinformation.
 12. A wireless network system comprising a hub station anda plurality of nodes, wherein the hub station comprises a hub stationmanagement table for managing unique information about each node basedon first update timing information, a detection means for detecting amodification in the node configuration, an update means for updating thehub station management table in accordance with the result of detectionby the detection means, and a transmitter for transmitting the firstupdate timing information to all of the nodes periodically, wherein eachnode comprises a node management table for managing the uniqueinformation about the node based on the first update timing information,a receiver for receiving the first update timing information, a datatransmission request means for comparing the first update timinginformation in the node management table of the node with the firstupdate timing information transmitted from the hub station and forrequesting, if the update timing information of the node is old, thetransmission of the unique information data, and an update means forupdating its own node management table based on the unique informationdata transmitted from the hub station in accordance with the request.